No it is not a valid Firefox update.

mpt63 said

security risk popup . is it valid?

much thanks

It is good to be skeptical of popup messages and check before installing. On the other hand, there is a brand new version 39.0.3 that was released earlier today that you could check for safely using either:

• "3-bar" menu button > "?" button > About Firefox
• (menu bar) Help > About Firefox

If your Firefox doesn't "see" the update yet, it usually is because it is on limited release the first day.

Firefox 39.0.3 is legitimate.

See also:

• https://www.mozilla.org/en-US/firefox/39.0.3/releasenotes/

tried that earlier, nothing. now there was . all is well now. thanks